PROJECT SUMMARY This goal of this K01 is to provide the mentorship and training for Dr. Sarah Gordon to become an independent investigator studying access to mental health services among low-income populations. Nationally, 1 in 8 women experience symptoms of postpartum depression (PPD), and rates of PPD are twice as high among women enrolled in Medicaid compared to commercially-insured women. This research examines the effects of postpartum Medicaid eligibility and benefit policies on PPD care among low-income women using a two-phase explanatory mixed-methods design. Aims 1 and 2 will analyze secondary data from a novel linked database of all payer claims data, birth certificates, and individual-level income data, consistent with NIMH's strategic objective to combine data from multiple sources to identify underserved groups. Using a regression discontinuity design, Aim 1 will evaluate the effects of retaining Medicaid eligibility beyond the pregnancy- related eligibility limit of 60 days postpartum on PPD screening, diagnosis, and treatment rates in the postpartum year. Aim 2 will use a difference-in-differences approach to measure the effects of Medicaid reimbursement for PPD screening during well-child visits on PPD screening, diagnosis, and treatment rates in the postpartum year, comparing outcomes among women who maintain versus lose Medicaid eligibility postpartum. Aims 1 and 2 will implement multi-level modeling techniques to examine county-level moderators of policy effects. In Aim 3, I will conduct qualitative interviews with key policy informants, providers, and patient focus groups to explore how postpartum Medicaid policies impact access to PPD services. Purposive qualitative sampling will be guided by county-level moderators of policy effects observed in Aims 1 and 2 and a ZIP-code level geospatial cluster analysis of PPD screening and treatment rates. Dr. Sarah Gordon is an assistant professor at the Boston University School of Public Health. She has four key training objectives: (1) acquire content expertise in the organization and delivery of mental health services, with a focus on maternal mental health; (2) obtain skills in mixed-methods research; (3) develop expertise in qualitative data collection and analysis, and (4) acquire skills to measure and map area-level variation in policy effects. Postpartum mental health conditions are a leading cause of preventable postpartum maternal morbidity and mortality. The goal of this proposal is to examine the effects of Medicaid policies in order to increase detection and treatment of PPD, thereby improving postpartum mental health. This research aligns with NIMH's high priority research area on women's mental health during the perinatal period and is responsive to the NIMH Strategic Plan priority to strengthen the public health impact of NIMH research by testing approaches for reducing empirically documented disparities in care access for socioeconomically disadvantaged persons.